I have 2 database (AWS Aurora Postgres) instances – reader instance and writer instance. There are 2 different connection strings for the instances and I want to utilize both instances.

I want to use reader instance to run DQL commands and writer instance run other commands.

I have a class called DatabaseContext which has the following code:

using Microsoft.EntityFrameworkCore;

namespace Com.Proj.Repository
{
    public class DatabaseContext : DbContext
    {
        public DatabaseContext(DbContextOptions<DatabaseContext> options) : base(options)
        {
        }

        public DbSet<Data> EngineData { get; set; }
        
        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Data>(entity =>
            {
                entity.HasKey(k => k.Id);
                entity.Property(t => t.Id).HasColumnName("id");
                entity.Property(t => t.Data).HasColumnName("data");
                entity.Property(t => t.Time).HasColumnName("time");
            });
        }
    }
}

I created another file with same exact code but with a different class name ReadDatabaseContext and in dependency injection, I did:

services.AddDbContext<ReadDatabaseContext>(options => options.UseNpgsql(readDbConnection, options => options.EnableRetryOnFailure(3, TimeSpan.FromSeconds(2), null))
                .UseQueryTrackingBehavior(QueryTrackingBehavior.NoTracking));

but I get an error:

instance of entity type cannot be tracked because another instance with same key value is tracked

I added this code in my ReadDatabaseContext:

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
    optionsBuilder.UseQueryTrackingBehavior(QueryTrackingBehavior.NoTracking);
}

I also added .AsNoTracking() wherever I am using the ReadDatabaseContext to read data.

But nothing worked.